Comparing 3 Types of Photosynthetic Plants

by Jason Amores Sumpter
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In this video, we're going to be comparing the three types of photosynthetic plants, which are the C three plants, the C four plants and the cam plants. And so it turns out that the vast majority of plant species are actually C three plants. And so the C three plants actually performed the standard photosynthesis process that we already covered in our previous lesson videos. And so the C three plants will perform the light reactions and the Calvin cycle exactly as we discuss them in our previous lesson videos. And so really, when it comes to the C three plants, really, there's nothing new here. It's really just review information from our previous lesson videos. And so the reason that C three plants are called C three plants is because the very first stable molecule that's produced during the Calvin cycle is a three carbon intermediate or a C three intermediate. That's why it's called C three plants and also during C three photosynthesis. C three plants are going toe on. Lee have one round of carbon fixation, and so carbon dioxide gas is on Lee going to be affixed to another molecule just one time, and that is during the Calvin cycle and also with C three plants. It turns out that the light reactions, the light reactions and the Calvin cycle are both going to occur in the same exact cell. And so that cell is going to be the missile Phil cell. And so when it comes to the C three plants, we can see a reminder of the C three plants down below in our image over here on the far left hand side. And so over here, what we have are the C three plants. And so when it comes to the C three plants again, it's really just review from our previous lesson videos. There's really nothing new when it comes to C three plants and C three photosynthesis. And so when it comes to the C three plants, it turns out that the light reactions and the Calvin cycle reactions are going to occur in the same exact sell. The missile fuel cell now notice that the light reactions is not being shown in any of these images here on we're focusing mainly on the Calvin cycle, and so in C three plants, the light reactions and Calvin cycle are going to occur in the same exact cell. And so notice that here we only have one cell and that is the missile Phil cell. And so you can see carbon dioxide coming into the Calvin cycle and glucose being produced here in the Calvin cycle. And so here we have C three leave it be, and that's because again C three plants just use the standard C three photosynthesis that we've already talked about. And so again, there's really nothing new here. It's all review, so c three leave it be with how we already discussed it. So now we're going to turn our attention to the next type of plant the C four plants. And so the C four plants and the camp plants have both evolved slightly different variations in the way that they perform photosynthesis. And so these slightly different variations that the C four and camp plants have evolved have allowed them to withstand hot temperatures by avoiding or minimizing photo respiration. And so we're gonna focus in on the C four plants first. So the C four plants are called C four plants because the very first molecule that's gonna be made is a four carbon intermediate, F four C intermediate, or a C four intermediate. And one major difference between C three and C four plants is that in terms of the number of carbon fixation rounds, the C four plants used to carbon fixation rounds instead of just one carbon fixation round like C three plants. And so we'll be able to talk about these carbon fixation rounds down below once we get to our image. Now, what's also another really big difference between C four plants and the C three plants that were used to is that C four plants. The light reactions and the Calvin cycle reactions occur in different cells, and so we'll be able to see this down below in our images well of the C four plants. And so unlike the C three plants, where the light reactions in the Calvin cycle reactions occur in the same cell with C four plants, the light reactions will occur in one cell type, and the Calvin cycle reactions will occur in a different cell type, and so they occur in different cells. Now this four carbon intermediate here is actually going to be the key to allowing C four plants to minimize photo respiration. And that's because this four carbon intermediate this foresee intermediate or C four intermediate eyes going to be useful in supplying additional carbon dioxide. Co two when carbon dioxide levels get really, really low from closing the Samata in warmer and drier temperatures. And so let's take a look at our image down below right here in the middle image. This is where we are showing you the C four plants and so we could go ahead and label them as the C four plants and, uh, standard example of C four plants are corn on DSO. What you'll notice is that in, um, C four plants, uh, the, uh there is going to be the light reactions and the Calvin reaction. They're going to occur in different cells. So notice here, what we have are two different cells. We have the mess of Phil cells, which are up above right here and then down below. What we have are the bundle sheath cells. And so those cells are down here and notice that the bundle she sells down below are the ones that will be performing the Calvin Cycle and the mess of Phil cells up above here are the ones that are actually going to be performing the light reactions and also in C four plants. There is going to be two rounds of carbon fixation, and so you can see here in the mess hall Phil cells. Carbon dioxide is going to be able to come into the missile Phil cell, and it's going to be a fixed to a three carbon molecule toe make a four carbon intermediate and the Foresee Intermediate. The C four intermediate is really why these plants are called C four plants. And so this foresee Intermedia is really, really important because what it does is it's fixing carbon dioxide, uh, and storing carbon dioxide as this four carbon intermediate. And so whenever carbon dioxide levels get really, really low, uh, this four carbon intermediate can be a supply can provide additional carbon dioxide so you can see CO two. Production here is able to occur, and the four carbon intermediate is able to be essentially converted to, ah, supply additional carbon dioxide whenever they get low, and this carbon dioxide, ultimately it's going to make its way into a second cell again. The bundle sheath cell and the bundle she sell is going to fix the carbon dioxide here a second time in the Calvin cycle to produce glucose. And so, ultimately, what we can see is that carbon dioxide or CO two is getting fixed up here in the mess hall Phil sell to form a foresee intermediate once, and then the foresee intermediate is really just a way to store carbon dioxide. So whenever carbon dioxide gets low, carbon dioxide production can occur. So here we have our co two molecule again, and the co two molecule can get fixed a second time in the Calvin cycle within the bundle sheath cell. Now, one way to help you remember that C four plants will use two different cells. The Missile Phil cell and the bundle she sell is to realize that see, fours are actually explosives like bombs. So if you ever if you know anybody that plays video games like call of duty or something like that, you'll know that C four czar explosives or bombs. And so when you think of C four plants, uh, even though really, C four plants have nothing to do with explosives, you can think of these explosives and what explosives do or bombs do when they explode, they basically break things up into pieces. And so when you think of C four plants, you can think of C four explosives and think of things getting broken up into pieces. And really, that's what we have here. We have, uh, two pieces. We've got the missile, Phil, sell peace, and we've got the bundle sheath sell piece down below. And so the C four plants are gonna be different in this respect of having two different cells utilized. And so now what we're going to do is move onto our third and final type of plant, which are the cam plants. And the camp plants are similar to the C four plants and that they also form a four carbon intermediate a foresee intermediate, just like the C four plants, dio. But the camp plants are different. Um, well, actually, the camp plants are similar to the C four plants and that they have a four carbon intermediate and that they have two rounds of carbon fixation. So this is how they are similar right here. But what's different between the C four and the camp plants is that the cam plants have the light reactions and the Calvin cycle reactions in the same cell. And so the same cell is going to be similar to how the C three plants performing. But the camp plants again. They're different than the C three plants because they form a four C intermediate that's different than C three, and they also have two rounds of carbon fixation, which is again different than the C three. But really, what makes the cam plants so unique is that the carbon fixation rounds these two carbon fixation rounds are going to occur at different times of the day. And so essentially, what's going to happen is that the stone Omada of camp plants are going to be open. They're going to be in the open position during the night when the temperatures are cooler, and then the stoma are going to change to their clothes position during the day when the temperatures Erhard hotter so that they can avoid dehydration. And so let's take a look here at our camp plant image down below, over here on the right hand side, and so we could go ahead and label these as the cam plants and a classic example of cam plants are going to be CAC Tie or a cactus like what you see in the desert. And so it's important to note here is that here with the camp plants, there's Onley, one cell type. Here, we only have the meself ill sell. So there's Onley, one cell type, unlike the C four plants, which it again, they have to sell types the bundle sheet and the missile Phil cells. So the camp plants only have one cell type, and they still fixed carbon twice so you can see carbon dioxide here is gonna make its way in and get fixed and form a four c intermediate similar toe. How there's a four c intermediate formed N C four plants, and this foresee Intermediate is again gonna act as a storage form of carbon dioxide. So when carbon dioxide levels get low, this foresee intermediate can provide additional carbon dioxide or CO two production, and then this carbon dioxide can be fixed a second time here in the Calvin cycle toe form glucose. And so what you'll also notice is that the carbon fixation is occurring at different times of the day. the first carbon fixation is occurring at night, which you can see up above here. And then the second carbon fixation right here is occurring during the day, and so ultimately, what happens is is again at night, when the temperatures in the desert are much, much cooler. The camp plant can have its the Mata Open without risking dehydration. And so when the Samata are open, carbon dioxide can come in and the plant can store Ah whole bunch of carbon dioxide at night as foresee intermediates. And then when the daytime comes around on, the temperatures get much hotter. The camp plant needs to close its tomato and when it closes its tamada. The carbon dioxide levels get low within the camp plant, however, because at night it's stored a whole bunch of four carbon intermediates. The four carbon intermediate can provide carbon dioxide during the day so that the Calvin cycle can run during the day and again perform uh, Calvin cycle to create glucose. And so, ultimately, the key feature here of the camp plants is that they are going to occur at different times. The day 11 carbon fixation occurs at night. The second carbon fixation occurs during the day, and so something that can help remind you of what the camp plants do is tow. Think that cam plants are kind of like a camel and camels. We know they live in really hot and dry environments like desserts. And so if you think of a camel wearing pajama XYZ, then you'll know that the this will help remind you that camp plants will perform their carbon fixation at different times of the day. The first carbon fixation is going to occur at night, and that can help remind you of the pajama Is can help remind you of that. And then, of course, the second carbon fixation is going to occur during the day. And so really, this is our brief introduction that's comparing the three types of photosynthetic plants to see three versus the C four versus the camp plants, and we'll be able to get some practice applying the concepts that we've learned here as we move forward in our course. So I'll see you all in our next video